- Haskell-Cafe - Haskell.org

typeclass for rest resource clients
by Jan von Löwenstein 01 Apr '17

01 Apr '17

Hi, for a project of mine I want to abstract away the rest resources (client side) and provide a stub implementation of the backend that I can use for testing. I thought about a StateT based stub instance, however one of the methods besides the usual crud stuff should be `waitFor` so that I can wait for resources to reach a certain state. Very concretely I want to create kubernetes pods and have my code wait until the pod is `Running`. What would I have to throw into the mix in order to have a stub that creates a pod and only later changes the status to `Running`? Any thoughts, advice or hint? Best Jan

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GHCI says we all drink left-handed
by Andreas Abel 01 Apr '17

01 Apr '17

GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help Prelude> data Handed = Handed Prelude> let drink beer = beer Prelude> all drink (Left Handed) True -- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel(a)gu.se http://www.cse.chalmers.se/~abela/

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Re: [Haskell-cafe] [accelerate-haskell] [ANN] Accelerate 1.0
by Trevor McDonell 01 Apr '17

01 Apr '17

Yep, it is just hard coded, but to be fair there have been very few new Accelerate backends. It does pull in extra dependencies though, if you forget to add the appropriate `-f-X` flag. The type class approach you mention sounds like how the LLVM-based packages are architected. -Trev On Fri, 31 Mar 2017 at 20:46 Henning Thielemann < googlegroups(a)henning-thielemann.de> wrote: > > On Fri, 31 Mar 2017, Trevor McDonell wrote: > > > * accelerate-fft: FFI bindings to discrete Fourier transforms (FFTW > and cuFFT) > > (https://hackage.haskell.org/package/accelerate-fft) > > I was curious how you solved the problem of addressing target specific > implementations of functions like the FFT. Looking at the source code it > looks like you have hard-coded a selection of back-ends. I hoped that we > would be able to specify back-end capabilities via a type-class. This way > the user could add more back-ends with their respective FFT > implementations. Maybe that's stuff to be defered to Accelerate-2.0. :-)

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ANN: hledger 1.2
by Simon Michael 01 Apr '17

01 Apr '17

I'm pleased to announce hledger 1.2, on schedule. Thank you to release contributors Peter Simons, Stefano Rodighiero, Moritz Kiefer, Pia Mancini, Bryan Richter, Steven R. Baker, Hans-Peter Deifel, Joshua Chia, Joshua Kehn, Michael Walker, and especially Mykola Orliuk and Justin Le! Notable user-visible changes in this release: new commands list, more powerful balancesheet/incomestatement/cashflow commands, more parseable print output, better --pivot, basic automated postings and periodic transactions support, more and easier addons, bugfixes. Full release notes: http://hledger.org/release-notes#hledger-1.2 The next major release is scheduled for June 30. hledger (http://hledger.org) is a dependable, precise, cross-platform program for tracking money, time, or any other commodity, using double-entry accounting and a simple plain text file format. It is a haskell reimplementation of Ledger, provides command-line, curses and web interfaces, and aims to be a robust, practical tool for daily use. To install this release: Get stack, eg from http://haskell-lang.org/get-started $ stack install --resolver=nightly hledger [hledger-ui] [hledger-web] [hledger-api] $ ~/.local/bin/hledger or see http://hledger.org/download for more installation options. Our IRC channel is #hledger on Freenode, and you can find out more at http://hledger.org. I hope you enjoy hledger and that it helps you achieve your goals. If you have benefitted from hledger, please give back and make it stronger! Donate using one of the funding links on the home page, give feedback, report bugs, send pull requests, write about it, etc. Best! -Simon

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[ANN] Accelerate 1.0
by Trevor McDonell 31 Mar '17

31 Mar '17

Friends, After much delay, it is my pleasure to announce the release of Accelerate 1.0. Accelerate is an embedded language for computations on dense, multidimensional arrays. Computations are expressed in the form of parameterised collective operations, such as maps, folds, and permutations. These computations are online compiled and can be executed on a range of architectures, such as multicore CPUs and GPUs. This release includes updates to a number core and support packages: * accelerate: Defines the core language (https://hackage.haskell.org/package/accelerate) * accelerate-llvm-native: Accelerate backend to execute computations on multicore CPUs ( https://hackage.haskell.org/package/accelerate-llvm-native) * accelerate-llvm-ptx: Accelerate backend to execute computations on CUDA GPUs (https://hackage.haskell.org/package/accelerate-llvm-ptx) * accelerate-llvm: For developing new backends targeting LLVM (https://hackage.haskell.org/package/accelerate-llvm) * accelerate-io: Conversions between Accelerate arrays and other formats (including vector and repa) (https://hackage.haskell.org/package/accelerate-io) * accelerate-fft: FFI bindings to discrete Fourier transforms (FFTW and cuFFT) (https://hackage.haskell.org/package/accelerate-fft) * accelerate-bignum: Fixed-width large integer arithmetic (> 64-bits) (https://hackage.haskell.org/package/accelerate-bignum) * accelerate-examples: Computational kernels and example applications, as well as regression test suite (https://hackage.haskell.org/package/accelerate-examples) * mwc-random-accelerate: Generate Accelerate arrays filled with pseudorandom numbers (https://hackage.haskell.org/package/mwc-random-accelerate) * gloss-accelerate: Generate gloss pictures from Accelerate (https://hackage.haskell.org/package/gloss-accelerate) * gloss-raster-accelerate: Parallel rendering of raster images and animations (https://hackage.haskell.org/package/gloss-raster-accelerate) * colour-accelerate: Colour representations in Accelerate, including RGB, sRGB, HSV and HSL (https://hackage.haskell.org/package/colour-accelerate ) * lens-accelerate: Lens operators for Accelerate types (https://hackage.haskell.org/package/lens-accelerate) * (soon) linear-accelerate: Linear vector spaces in Accelerate (https://hackage.haskell.org/package/linear-accelerate) (pending https://github.com/ekmett/linear-accelerate/pull/4) The (still under construction) acceleratehs.org website includes some installation instructions and a short tutorial to help you get started. * http://www.acceleratehs.org/get-started.html * http://www.acceleratehs.org/examples/mandelbrot.html If you find a bug or have a question, head over to the GitHub issue tracker or mailing list. * https://github.com/AccelerateHS/accelerate/issues * accelerate-haskell(a)googlegroups.com We welcome new contributors, so please contact us if you would like to get involved!

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Compose Conference Call for Participation [NYC, May 18-19]
by Gershom B 31 Mar '17

31 Mar '17

=============================================== Call for Participation Compose Conference 2017 May 18-19 2017 New York, NY http://www.composeconference.org/2017 =============================================== The practice and craft of functional programming :: Conference Compose is a conference for typed functional programmers, focused specifically on Haskell, OCaml, F#, SML, and related technologies. Typed functional programming has been taken up widely, by industry and hobbyists alike. For many of us it has renewed our belief that code should be beautiful, and that programming can be as enjoyable as it is practical. Compose is about bringing together functional programmers of all levels of skill and experience — from technical leads to novices, and from long-time hackers to students just getting started. It will feature a keynote by Emily Riehl on aspects of category theory and computation, and two days of great talks. * Invited Talks Emily Riehl: TBA * Local Information (venue): http://www.composeconference.org/2017/ * Accepted Talks and Tutorials Barry Burd - Teaching Haskell David Rhodes - Learning F#: Case study with branch and bound Edmund Cape - Multiplying by 1 - an important form of computation and how it reveals distinctions between kleislis Enzo Alda, et al. - Reactive Sheets: an intuitive approach to functional‑reactive computing Hezekiah Carty and Chris Donaher - Distrest - REST access to distributed services Hongbo Zhang - BuckleScript: Making functional programming accessible to JavaScript developers Jennifer Paykin, Kenneth Foner, Antal Spector-Zabusky - `choose` Your Own Derivative Joachim Breitner - Lock-step simulation is child’s play Martín Ceresa, Gustavo Grieco - QuickFuzz Testing for Fun and Profit Michael Chavinda - Android programming in Froid Nikhil Barthwal - Implementing an Event-Driven Microservices Architecture in F#: A case study of Jet.com Nikita Volkov - New Hasql - a simpler, safer and faster Postgres client Sebastien Mondet - Typed-Tagless Final Bioinformatics Stephen Compall - Working with Monads in OCaml Stuart Popejoy - Smart Contracts and Formal Verification with Z3 with Pact Yaron Minsky - Data Driven UIs, Incrementally * Full abstracts: http://www.composeconference.org/2017/program * Registration: http://composeconference.eventbrite.com * Follow @composeconf on twitter for news: https://twitter.com/composeconf * On freenode irc, chat with fellow attendees at #composeconference * Corporate sponsorships are welcome. Current sponsors list forthcoming. * Policies (diversity and anti-harassment): http://www.composeconference.org/conduct * Email us with any questions at info(a)composeconference.org * Please forward this announcement to interested parties and lists.

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Request for white paper
by Michael Litchard 30 Mar '17

30 Mar '17

I'm looking for a freely available version of the below paper. Google Scholar points me to 7 versions, all of which are behind a paywall. Stefan Kahrs, "Red-black trees with types", Journal of functional programming, 11(04), pp 425-432, July 2001

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Call for participation - Programming Languages Mentoring Workshop (PLMW)
by Tobias Grosser 29 Mar '17

29 Mar '17

We invite early graduate students and undergraduates to apply for a scholarship and to participate in the Programming Languages Mentoring Workshop (PLMW) in Barcelona, Spain on Sunday, June 18, 2017. The purpose of this mentoring workshop is to encourage and prepare graduate students and senior undergraduate students to pursue careers in programming language research. The workshop also includes specific mentoring opportunities for students who belong to traditionally underrepresented populations, including women, people of color, students with disabilities, and first-generation students. Throughout the day, we’ll have technical sessions, to discuss cutting-edge research in programming languages; and mentoring sessions, to help you learn about, prepare, and succeed in your research career. You’ll also have the opportunity to talk with top programming language researchers and other students interested in programming language research. This workshop is part of the activities surrounding the Programming Languages Design and Implementation (PLDI) conference and takes place the day before the main conference. One goal of the workshop is to make the PLDI conference more accessible to newcomers. We hope that participants will stay through the entire conference. Other events that follow the workshop include the Programming Languages Summer School and the European Conference on Object-Oriented Programming (ECOOP). Scholarship funds are available for students to attend PLMW@PLDI. These scholarships should cover reasonable expenses (airfare, hotel, and registration fees) for attendance at both the workshop and an associated event (such as the PLDI conference or the summer school), but are limited. We welcome students with alternative sources of funding to attend as well; but everyone who plans to attend needs to apply. Apply for a scholarship and to participate at PLMW@PLDI: https://goo.gl/forms/80aacyFiXNFNnPqA3 The deadline for full consideration of funding is SATURDAY, APRIL 15. Selected participants will be notified by APRIL 29 and will need to pre-register and commit to attending the workshop by MAY 10. Applicants who apply after April 15 but by May 15 may be eligible to receive funding, if funds remain, and will be notified by by May 29. Additionally, if you are currently a student in the United States who cannot (or will not) travel due to concerns about US travel restrictions, we encourage you to apply and let us know. We may be able to arrange another form of mentoring for you. We look forward to seeing you! The PLMW@PLDI Organizers Michael Carbin, MIT Stephen Chong, Harvard University Işıl Dillig, The University of Texas at Austin Ben Wiedermann, Harvey Mudd College

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Queue which tracks actual in-memory element size?
by Bardur Arantsson 29 Mar '17

29 Mar '17

Hi all, So we have the TBQueue[1] which tracks the number of elements, but does anyone know if there's an equivalent queue which the actual combined size of the elements? (I'd be quite happy if it used "gsize" or similar, but I suppose the ideal would be if I could supply a "size estimator" function.) It seems like an obvious generalization of TBQueue[2], but my Google-fu is letting me down at the moment. Regards, --- [1] https://hackage.haskell.org/package/stm-2.4.4.1/docs/Control-Concurrent-STM… [2] TBQueue would be the equivalent of estimating every element to have size 1.

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[ANN] wiringPi-1.0.1
by Patrick Pelletier 29 Mar '17

29 Mar '17

https://hackage.haskell.org/package/wiringPi https://github.com/ppelleti/hs-wiringPi The most significant addition in this version is the wiringPiISR function, which makes it possible to get a callback when an input pin changes, thus avoiding the need to poll. In a future version, I might add a higher-level facility on top of this, such as the ability to update a TVar when an input changes. (Let me know if you have any thoughts on this.) New in 1.0.1: * Examples for Pi-LITEr and Fish Dish boards. * Added piGpioLayout as a synonym for piBoardRev, to reflect the name change in version 2.36 of the C library. * Addition of wiringPiISR function. (Contributed by Satoshi Ogata.) * Improvements to documentation and examples. About wiringPi: This is a Haskell binding to the wiringPi library, which allows you to interface with the GPIO pins on the Raspberry Pi. Unlike some other solutions for using the Raspberry Pi's GPIO pins, wiringPi provides access to more advanced features, such as enabling the internal pull-up or pull-down resistors. --Patrick

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